Background: It is a constitutional right to receive health care, including mental health care, while incarcerated. Yet, even basic evidence-based mental health care practices have not been routinely integrated into criminal justice (CJ) settings. Strategies from implementation science, or the study of methods for integrating evidence-based practices into routine care, can accelerate uptake of established interventions within low-resource, high-need settings such as prisons and jails. However, most studies of mental health practices in CJ settings do not use implementation frameworks to guide efforts to integrate treatments, systematically select or report implementation strategies, or evaluate the effectiveness of strategies used. Case presentations: After introducing implementation science and articulating the rationale for its application within CJ settings, we provide two illustrative case examples of efforts to integrate mental health interventions within CJ settings. Each case example demonstrates how an implementation framework either was applied or could have been applied to promote intervention adoption. The first focuses on poor implementation of a mental health screener in a county jail, retrospectively highlighting how use of a determinants framework (e.g., the Consolidated Framework for Implementation Research [CFIR]) could help staff identify factors that led to the implementation failure. The second describes an investigator-initiated research study that used a process framework (the Exploration, Preparation, Implementation, Sustainment [EPIS] framework) to systematically investigate and document the factors that led to successful implementation of a psychotherapy group for survivors of sexual violence in a women's community corrections center. Both are presented in accessible language, as our goal is that this article can be used as a primer for justice health researchers, community partners, and correctional leadership who are unfamiliar with implementation science. Conclusions: Scientific research on the application of implementation science to justice settings is growing, but lags behind the work done in health systems. Given the tremendous need for mental and behavioral health intervention across the full spectrum of justice settings, information on how to successfully implement evidencebased intervention and prevention efforts is sorely needed but possible to obtain with greater integration of knowledge from implementation science.